﻿using System.Diagnostics;
using System.Windows.Input;

namespace Aliphant.Mvvm.XEvent.UI
{
    public class UICommand<T> : ICommand
    {
        #region Fields

        readonly Action<T?> _execute;
        readonly Predicate<T?>? _canExecute;

        #endregion // Fields

        #region Constructors

        public UICommand(Action<T?> execute)
            : this(execute, null)
        {
        }

        /// <summary>
        /// Creates a new command.
        /// </summary>
        /// <param name="execute">The execution logic.</param>
        /// <param name="canExecute">The execution status logic.</param>
        public UICommand(Action<T?> execute, Predicate<T?>? canExecute)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");

            _execute = execute;
            _canExecute = canExecute;
        }

        #endregion // Constructors

        #region ICommand Members

        [DebuggerStepThrough]
        public bool CanExecute(object? parameter)
        {
            return _canExecute == null || _canExecute.Invoke(parameter == null ? default : (T)parameter);
        }

        public event EventHandler? CanExecuteChanged
        {
            add => CommandManager.RequerySuggested += value;

            remove => CommandManager.RequerySuggested -= value;
        }

        public void Execute(object? parameter)
        {
            try
            {
                _execute(parameter == null ? default : (T)parameter);
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex);
            }
        }

        #endregion
    }
}
